diff --git a/modules/amv/intercompare.py b/modules/amv/intercompare.py
index 0f23e8bb213c3046d73a555b76c790cf18ab1ce6..d6b597c317aaaac66111ed89f5da101a7d1f0aae 100644
--- a/modules/amv/intercompare.py
+++ b/modules/amv/intercompare.py
@@ -1144,7 +1144,7 @@ def best_fit_altitude(amv_spd, amv_dir, amv_alt, amv_lat, amv_lon, fcst_spd, fcs
     if good_constraint == 1:
         bf_tup = (sat_wind_best_fit_u, sat_wind_best_fit_v, sat_wind_best_fit_alt, 0)
     else:
-        bf_tup = (None, None, None, flag)
+        bf_tup = (np.nan, np.nan, np.nan, flag)
 
     if verbose:
         print('*** AMV best-fit ***')